کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5417683 1506942 2008 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Effects of substituents on the electronic properties of polyacetylenes
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
Effects of substituents on the electronic properties of polyacetylenes
چکیده انگلیسی
Hartree-Fock quantum mechanical calculations [at the RHF(ROHF)/6-31G(d) level] were performed to determine the electronic structure (ionization energies, electron affinities and singlet-triplet transition energies, ΔE(S0→T1)) in a series of polyacetylenes with terminal substituents (neutral and charged), NH (NH2+), NH2 (NH3+), SH (S−), and SO3H (SO3−), for oligomers with between 2 and 30 conjugated double bonds. Neutral substituents had relatively modest effects on the electronic properties, primarily in systems with less than ∼8-10 double bonds. The positively and negatively charged substituents were found to exert profound influences on these properties, which persisted in even the largest species studied. Negative terminal substituents lowered the ionization energies (relative to PA) by as much as 5 eV, even in systems with 30 double bonds, and the positive substituents decreased electron affinities by an equivalent amount. Both positive and negative substituents decreased values of the singlet-triplet transition energy by ∼1-1.5 eV relative to the value in pristine PA. These effects were explained on the basis of a simple model of the effects of electron donors and acceptors on the frontier orbital (HOMO/LUMO) energies and charge distributions.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Structure: THEOCHEM - Volume 859, Issues 1–3, 30 June 2008, Pages 37-45
نویسندگان
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